In a function call, what is the operator, and what are the operands?

Question

I am trying to understand some basics of C. KRC's The C Programming Language says

A function call is a postfix expression, called the function designator, followed by parentheses containing a possibly empty, comma-separated list of assignment expressions (Par.A7.17), which constitute the arguments to the function.

1. In a function call, what is the operator, and what are the operands?

   Is () the operator?

   Is the function name an operand?

   Are the arguments inside () operands?

2. Is a function designator a synonym of a function call?

Thanks.

Answer 1

In a function call, () is an operator just like [] is an operator when accessing an array element.

6.5.2 Postfix operators

Syntax
1 postfix-expression:
primary-expression
postfix-expression [ expression ]
postfix-expression ( argument-expression-listopt )
postfix-expression . identifier
postfix-expression -> identifier
postfix-expression ++
postfix-expression --
( type-name ) { initializer-list }
( type-name ) { initializer-list , }

argument-expression-list:
assignment-expression
argument-expression-list , assignment-expression  

Operand for this operator is the function name (or a pointer to the function).

Are the arguments inside () operands?

No. As per the C standard the list of expressions specifies the arguments to the function.